parte 
I915.] F.H. Gravety: Indian Mygalomorph Spiders. 267 
The only remaining genus of Aviculariinae found in the Indian 
Peninsula or Ceylon is Chilobrachys, the most highly specialized 
genus of the group Selenocosmieae. The whole history of the 
evolution of this ground-dwelling genus can be read in the forms 
inhabiting the countries north and east of the Ganges to-day; and 
there seems no reason to doubt that its evolution took place 
there. The primitive forms left there are extremely rare, having 
no doubt suffered in the struggle for existence with their more 
highly specialized relatives. The most highly specialized genus 
of these has spread into the Indian Peninsula and Ceylon, a fact 
which probably accounts for the concentration southwards and 
westwards of the Indian Ischnocoleae and the Thrigmopoeeae. 
The evolution of the Selenocosmieae has already been dealt 
with from a primarily zoogeographical point of view (Gravely, 
1915), with the results indicated in the above summary. The 
morphological point of view must now be more fully considered. 
Reference has been made above to the existence in parts of the 
Oriental Region north and east of the Ganges of a few primitive 
species of Aviculariinae. These appear to be extremely rare, and 
those hitherto described are known to me from descriptions only. 
There is, however, in the Indian Museum collection, a single imma- 
ture specimen from the Darjeeling District which must be asso- 
ciated with them. The species already described are two in 
number; both were collected by Fea in Burma, and referred by 
Thorell to the genus /schnocolus (1896, pp 170-175). More recently 
Simon (Vol. II, p. 925) has shown that this genus /schnocolus must 
be restricted to species from the Mediterranean and Ethiopian 
regions; but he makes no mention of the position to be assigned 
to the Burmese forms. In describing the labium of one of these, 
“‘ Ischnocolus’’ brevipes, Thorell says, ‘‘ apice fascia transversa sat 
lata granulorm densissimorum praeditum.’’ With regard to the 
labium of the other, ‘‘ Ischnocolus’’ ornatus, which he described — 
from two immature specimens, he says, ‘‘ quod .... apice minus 
dense granulosum est—an ita etiam in adultis?’’ Now the pre- 
sence of a densely granular transverse band on the apex of the 
labium is characteristic of the Selenocosmiae. In all other 
Oriental groups of Aviculariinae the anterior part of the labium 
is more sparsely armed. The distinction, although qt&ntitative, 
is very marked; and except perhaps in very young and imper- 
fectly hardened specimens such as no one could think of naming, 
a glance at the labium is sufficient to show whether a specimen 
belongs to the Selenocosmieae or not. 
The only Burmese species in which the labium is sparsely 
armed, other than those referred by Thorell to the genus /schnoco- 
lus, are those comprising the group Ornithoctoneae, which are 
separated from all other Oriental species by the densely hairy 
outer surfaces of their chelicerae. That the occurrence of a 
sparsely armed labium in a Burmese species without externally 
hairy chelicerae struck Thorell as very remarkable, seems to be 
indicated by his suggestion that its presence was due to the imma- 
